This invention relates to tape cassette assembly and, more particularly, to a method and apparatus for assembling tape cassettes.
Tape cassettes are usually assembled on an assembly line, wherein various components are installed in a cassette base or cover and the base and cover are mated.
As an example, a conventional VHS video cassette assembly line generally includes the following parts, the order of which may be varied, as known in the art: conveyor belts for moving cassette covers and cassette bases from station to station; a station for installing a multi-piece reel lock in the base; a station for installing a dust door and a dust door spring on the cover; a station for applying lubricant to posts on the base which receive plastic rollers; a station for installing the plastic rollers; a station for locating guidepost sleeves on other posts formed on the base; a station for removing a recording prevention tab from the base exterior; a station for correctly orienting the guidepost sleeves on the posts; a station for installing a dust door latch and spring into the base; a station for attaching a reel leaf spring on the cover; a station for installing a pair of leadered tape reels (without tape) into the cassette base, i.e., one end of a leader is applied to the hub of one tape reel and the other end of the leader is applied to the hub of the other tape reel; a station for installing a pressure flap in the base; and a station for mating and securing the cover and the base.
Once the cassettes are assembled, they are usually sold to another company which then automatically attaches blank tape to the leader and loads the cassette by winding the tape reels using a tape loading machine, such as described in U.S. Pat. Nos. 4,572,450 or 4,512,904. The cassette can then be sold as a blank cassette or recorded with, e.g., a movie and sold as a pre-recorded tape cassette.
Despite the fact that millions of video cassettes are produced on such an assembly line each year, this line is characterized by the following drawbacks.
Specific to the leader application station, the leader is measured, cut and applied to the hubs via leader clips which catch the leader ends between the clips and corresponding recesses formed in the hubs, and then the tape reels are wound. The measuring, cutting and applying steps can be manual or automatic. The leader specifications set by JVC, the licensor of the VHS video cassette, are very strict regarding leader length because the automatic tape loading machines must be able to efficiently and quickly grasp the leader, attach tape thereto and load the tape in the desired length by winding the tape reels. Further, in conventional practice, the adjacent reels of respective pairs are spaced apart. A double cut is made between these pairs, which leaves about a 11/2 inch scrap of leader for each pair. This scrap represents a significant costly waste since millions of cassettes are manufactured.
However, the conventional manual or automatic methods of measuring, cutting and applying the leader often result in irregular leader lengths, thereby frustrating automatic tape loading, increasing rejects, increasing costs, decreasing output, etc.
More generally, this conventional assembly line is relatively slow, requires significant maintenance and operator assistance, takes up a large amount of space, and is relatively costly. Most importantly, the conventional system usually uses and arm which catches and indexes a shell along the assembly line. The arm then moves back to its original position and catches another shell, etc. This back-and-forth motion is redundant and takes up valuable assembly time.
Thus, the prior art still does not provide the most cost-or time-efficient assembly line for producing video cassettes.